Conventionally swaging or crimping presses employ die elements that are arranged around a work zone and are forced to move radially inwardly during a crimping or swaging operation to press against the metal collar, ferrule or the like. Conventionally die elements in such machines are selectably attachable to die shoes which are moved typically under high loads by a hydraulically operated piston acting simultaneously on all of the die shoes radially inwardly during a crimping or swaging process. Such machines and arrangements are described in Australian Patent Specification Nos. 2001276155, 2004900774 and 2006230741. Conventional die elements include a body portion with a radial inner work engaging surface that extends axially and has a concave curved surface transverse to the axial direction. In modern machines of this type, it is usual to provide eight such die elements circumferentially about the work zone but it is known to utilise any number of such cooperating die elements from two upwards including uneven numbers of the die elements. The die elements are generally removable so that they can be replaced with other types of die elements depending on the task required to be performed and the work element intended to be swaged or crimped. A collection of die elements to make up a complete arrangement may be termed a “die set” and typically a swaging or crimping press may be supplied with a variety of die sets that in a final inner position of the die elements will provide smaller or larger circumferences defined by the work element engaging surfaces. This enables work elements of differing sizes to be worked on and further to reduce the diameter of the work element (collar, ferrule or the like) gradually or in steps by utilising differing die sets. When the die elements of any die set are fully closed (radially innermost position), the internal diameter (termed “closure diameter”) becomes the Die Set Number. Controlling the machine such that in the reduction process, the reduction operation stops at a defined distance from the closure diameter (termed “Offset Value”), provides a finished diameter of Die Set Number and Offset Value.
Each die set can with a limited range of Offset Values, crimp a ferrule/collar to a range of finished diameters limited by, the internal curvature of the work engaging surfaces of the die elements matching the performance requirements of the finished crimped ferrule/collar; the amount of ferrule surface area that is positioned between the die elements, not directly beneath the die element work engaging surface; and the final crimped ferrule/collar no longer having a general cylindrical shape. In the crimping process, the die elements move in radially, however, they contact the work element (ferrule, collar or the like) only at the axial edges of the die elements. As the die elements move further radially inwardly to the required final diameter, the work element strains in the following manner. Metal directly beneath the die element does not compress due to the contact on the edges of the die element because the curvature of the work engaging surface of the die is always smaller than the curvature of an un-crimped work element (ferrule or collar). Moreover, metal of the work element between the die elements is squeezed as the edges of the die elements, which have imprinted the work element surface, contract. This causes the work element metal to “balloon” both externally and internally in those regions. The final result is a ferrule that is distorted, especially internally where in most instances it is preferred that it provides a uniform radial squeeze onto the hose surface on which it is engaged.